UN Secretary-General Ban Ki-moon has called for an easing of tensions between Iran and the West over Tehran's nuclear ambitions.

A war of words between Washington and Tehran has increased in recent days with Iran threatening the United States not to send naval vessels through the strategic Strait of Hormuz.

Ban called on both sides to "do their best" to defuse tensions in the region, and resolve their differences through talks.

Ban also said it was ultimately up to Iran to prove its nuclear program was solely for peaceful purposes.

The UN chief also said he remained "concerned" over a recent report by the UN nuclear watchdog, the International Atomic Energy Agency, suggesting there is a military dimension to Iran's nuclear program.

He called on Tehran to abide by UN Security Council resolutions demanding Iran stop enriching uranium.

It's failure to do so has resulted in Iran being slapped with four rounds of UN sanctions.